The Adafruit STEMMA Audio Amp is a super small mono amplifier is surprisingly powerful - able to deliver up to 2.5 Watts into 4-8 ohm impedance speakers. Inside the miniature chip is a class D controller, able to run from 2.0V-5.5VDC. Since the amp is a class D, it's very efficient (over 90% efficient when driving an 8Ω speaker at over half a Watt) - making it perfect for portable and battery-powered projects. It has built in thermal and over-current protection but we could barely tell it got hot. There's even a volume trim pot so you can adjust the volume on the board down from the default 24dB gain. This board is a welcome upgrade to basic "LM386" amps!

This board is a simplified version of our breadboard-friendly Adafruit Mono 2.5W Class D Audio Amplifier board. This version is designed to be 'plug and play' - with no soldering required. You can input the audio via the JST-PH 3 Pin connector - such as a pin header cable or one with alligator clips. The trade-off is that this board doesn't have differential inputs, instead the audio inputs are referenced to the power/signal ground wire.

The input to the amplifier goes through 1.0uF capacitors so you can have DC. The output is "Bridge Tied" - that means the output pins connect directly to the speaker pins, no connection to ground. The output is a high frequency 250KHz square wave PWM that is then 'averaged out' by the speaker coil - the high frequencies are not heard. All the above means that you can't connect the output into another amplifier, it should drive the speakers directly.

The board comes fully assembled and tested. We also include header to plug it into a breadboard and a 3.5mm screw-terminal blocks so you can easily attach/detach your speaker. You will be ready to rock in 15 minutes! Speaker is not included, use any 4 ohm or greater impedance speaker.

  • Output Power: 2.5W at 4Ω, 10% THD, 1.5W at 8Ω, 10% THD, with 5.5V Supply
  • 50dB PSRR at 1KHz
  • Filterless design, with ferrite bead + capacitors on output.
  • Fixed 24dB gain, onboard trim potentiometer for adjusting input volume.
  • Thermal and short-circuit/over-current protection.
  • Low current draw: 4mA quiescent and 0.5mA in shutdown (due to pullup resistor on SD pin)

Note: The terminal block included with your product may be blue or black.

This guide was first published on Jul 08, 2023. It was last updated on Jul 24, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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